Hi Michael.
TravelSupermarket.com is one that I have used before, just to get an idea of the variation of prices from airline to airline.
What I tend to do is not actually book through TravelSupermarket but just view the prices and then once I have an idea of what it might cost, visit the proper website, not through the link that TravelSupermarket give you as I have heard it doesn't work properly and I'm sure no-one wants their money to be lost through transaction.
They are very good at comparing all airlines that operate routes, both via certain airports or directly. As there is no direct link from LBA to Washington, it will probably bring up direct routes to MAN, but if you leave the 'Direct Flights Only' box un-ticked, it may bring up an alternative via Amsterdam for example and sometimes these can be cheaper than direct flights into MAN.
One important thing that you need to know, is the price that TravelSupermarket shows does not include extra's i.e. baggage, other surcharges e.t.c. and I would think that especially travelling from the US, it should be a thing to consider.
Hope this helps,
Regards,
Tom.
